Effect of combined human neutrophil cathepsin G and elastase on induction of secretory cell metaplasia and emphysema in hamsters, with in vitro observations on elastolysis by these enzymes.

To determine whether purified human neutrophil cathepsin G (Cat-G) can act by itself or in concert with purified human neutrophil elastase (HNE) in the induction of emphysema and bronchial secretory cell metaplasia (SCM), we gave golden Syrian hamsters 100 µg of HNE alone or in combination with either 100 or 200 µg of Cat-G. Other groups of animals received intratracheal doses of up to 600 µg of Cat-G alone. The severity of emphysema was determined from measurements of lung volumes, compliance, forced expiratory flow, and the mean linear intercept. The severity of SCM in the main airways was graded on sections stained by the alcian blue and periodic acid-Schiff reaction. The Cat-G was a weak inducer of SCM; significant SCM was produced by 400 and 600 µg but not by 100 or 200 µg or 200 µg of Cat-G. The Cat-G (100 and 200 µg) did not potentiate the SCM induced by 100 µg of HNE. The Cat-G alone did not produce emphysema, and neither 100 nor 200 µg of Cat-G potentiated the mild emphysema induced by 100 µg of ...